1. Field of the Invention
The invention relates generally to anaerobic processing of waste material and, more particularly, but not by way of limitation, to use of a biochemically enhanced hybrid anaerobic reactor (BEHAR) for processing of such as high strength industrial waste waters.
2. Description of the Prior Art
Treatment of waste by either aerobic or anaerobic processing is quite old and various types and sizes of digester have been developed for use in such systems. More recent developments have seen construction of more specific types of digester that are designed for clean-up of wastewater containing various impurities. U.S. Pat. No. 4,311,593 discloses a digester system for use with wastewater that is effluent from molasses fermentation processing. The wastewater is treated in an anaerobic vessel which includes high surface area media. The wastewater is directed downwardly through the media for interaction with microorganism biomass with production of methane while reducing oxygen demand of such material. Various nutrients may be added to the mixture in order to promote growth of the microorganisms. The sloughed biomass is recirculated from the bottom of the digester to the top thereof while the methane stream is selectively recirculated into the bottom of the digester and bubbled up through the media and wastewater therein. Preferably a nominal pressure is maintained on the digester to urge carbon dioxide produced in the process to remain in solution with the effluent.
U.S. Pat. No. 4,530,762 teaches an anaerobic reactor for wastewater treatment. The tank apparatus includes a reaction hood in a lower extremity that defines a mixing zone where influent water mixes with liquid and biological solids already in the zone beneath the hood. The reaction tank may include a fixed film media above the hood enclosure and the system utilizes a sludge thickener for concentrating the sludge removed from the tank. This anaerobic treatment process may be described as three distinct steps (A) acid fermentation, (B) acid regression, and (C) alkaline fermentation. U.S. Pat. No. 4,632,758 discloses yet another anaerobic treatment system wherein wastewater to be treated is introduced into the bottom of the reactor and forced upward over media surfaces wherein the waste is consumed by anaerobic digestion with usual by-product of methane and a biological sludge. Methane given off as a by-product of the anaerobic digestion may be used as a source of fuel for heating the reactor influent immediately before it is introduced into the reactor. Still further, the reactor effluent may be directed to a degassifier whereby entrained gas is released before introducing the degassified reactor effluent into a clarifier whereby the effluent's biological sludge will settle out. An alkaline substance such as bicarbonate may also be introduced to form a bicarbonate slurry in an amount sufficient to enhance the activity of the methane producing bacteria, but insufficient to effect directly the pH of the reactor contents.